EXTRACTION OF NATURAL COMPOUNDS FROM FICUS CARICA LEAVES AND THEIR USAGE IN THE GREEN SYNTHESIS OF BIOSILICA NANOPARTICLES

Project no. 28483 · Status: Kapanmış (Yayın bekleniyor) · 2023

Summary

This thesis focuses on the extraction of bioactive compounds from different types of Ficus carica (fig) leaves, the determination of their biological activities, and their potential applications. Leaves from the Sarılop and Bursa Black fig varieties were used. Conventional solvents such as water, ethanol, and ethanol-water mixtures were employed to extract compounds from the fig leaves, and optimal extraction conditions were determined. Independent variables such as solid-liquid ratio, ethanol concentration, extraction time, and temperature were analyzed using the response surface methodology (RSM). The responses included extraction yield, antioxidant capacity, and total phenolic content (TPC), all of which were optimized to achieve the highest performance.For Sarılop fig leaves, the optimal extraction conditions were determined as an 82% ethanol solution, 180 minutes of extraction time, an extraction temperature of 25°C, and a solid-liquid ratio of 0.01 g/mL. For Bursa Black fig leaves, the optimal extraction conditions were a 42% ethanol solution, 60 minutes of extraction time, an extraction temperature of 25°C, and a solid-liquid ratio of 0.01 g/mL.Following the determination of optimal extraction conditions, various natural deep eutectic solvents (NADES) were synthesized as eco-friendly solvents. These solvents included NADES based on choline chloride with acetic acid, lactic acid, and tartaric acid, as well as NADES containing glycerol, xylitol, and fructose. These solvents were applied for fig leaf extraction under previously optimized conditions (0.01 g/mL solid-liquid ratio, 25°C extraction temperature, and 180 minutes of extraction time). Among the tested solvents, NADES synthesized with choline chloride and acetic acid was selected as the most effective solvent based on the highest TPC value and was used for subsequent applications.The extracts obtained from fig leaves under optimal conditions were further utilized for the green synthesis of silica nanoparticles (SiNPs) as part of this study. Initially, rice husk ash (RHA), an industrial waste product, was used as a silica source. Sodium silicate solution was synthesized from RHA via extraction using a basic NaOH solution. This solution was then used as the silica precursor in the production of silica nanoparticles. The synthesis process was first optimized at pH 9 with a reaction temperature of 60°C and a duration of 6 hours. At Si:TPC molar ratios of 300–600, amorphous silica nanoparticles with a surface area of 237–280 m²/g, a pore diameter of 10 nm, and a particle size of 22–23 nm were produced. The band gap energies of these nanoparticles were measured between 1.47 and 1.49 eV. To achieve a more homogeneous particle distribution, experiments were conducted at different pH levels and Si:TPC molar ratios. The optimal conditions for obtaining monodisperse nanoparticles were determined as pH 7 and a Si:TPC molar ratio of 1200. Silica nanoparticles were synthesized using extracts obtained from different solvents under optimal extraction conditions, and the effects of the total phenolic compound profile on nanoparticle synthesis were examined. Amorphous silica nanoparticles with surface areas ranging from 88.86 to 706.26 m²/g and pore diameters between 3.94 and 11.10 nm were produced. The band gap energies of these nanoparticles varied between 1.00 and 4.10 eV, depending on the type of solvent used and the distribution of phenolic compounds.This thesis not only provides a sustainable method for extracting bioactive compounds from agricultural waste but also highlights the nanotechnological potential applications of these compounds in the healthcare industry. By integrating green chemistry and circular economy principles, this study contributes to sustainable scientific advancements.

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